Biowater: Innovative gray water treatment

Procasur November 14, 2023 Water Solutions
Biowater: Innovative gray water treatment

Solution type: Gray water treatment

  • Objectives: Increase the availability of water for irrigation of crops and animal husbandry.
  • Description: The reuse of gray water can represent more than half of residential water use, becoming an alternative water supply to face periods of scarcity for irrigation purposes. For this, a technology is used in which the biodegradation of organic matter is produced by a population of microorganisms and worms inserted in the filter layers of the system and, by doing so, the main pollutants of gray water are reduced.

 

Performance

In a household of five people, approximately 250 liters of gray water are generated per day. This represents a production of around 90 thousand liters of water per year, which is equivalent to almost two production tanks or nine tank trucks with a capacity of 10 m³ of water. The suitability of this gray water reuse technology is defined by criteria, guidelines and quality standards that seek to guarantee that it is carried out in a sustainable and safe manner from health and environmental aspects.

 

Components

The gray water that will be treated in the biofilter consists of water from the kitchen and showers. The biofilter is preceded by a masonry grease separator box, equipped with PVC inlet and outlet pipes, and is preceded by a treated gray water storage tank.

The biofilter has a downward flow, being composed of an initial layer of boulders, followed by crushed stone, washed sand, wood chips and humus. The treated gray water then passes to the covered storage tank to avoid the incidence of light and the subsequent proliferation of algae, mosquitoes and larvae, and safety.

Within the same technological idea, the Filter Garden was developed that imitates a flooded natural area (swamp, marsh, etc.), where plants adapted to water-saturated areas (technically called aquatic macrophytes) and microorganisms associated with the roots of These plants work together to remove nutrients and contaminants in a natural way.

 

Construction

For a residence of up to five residents, basically, a Filter Garden is a small lake (5 m long x 2 meters wide x 0.5 m deep) that is waterproofed by a flexible geomembrane (EPDM or Vinyl) and covered in the top and bottom with Bidim type geotextile blanket.

The lake is filled with a layer of coarse gravel (No. 2 or 3) at the bottom, and a layer of coarse sand at the top. In the sandy phase of the system, ornamental plants adapted to flooded areas are added. PVC pipes and connections are installed so that the wastewater to be treated enters through the top and the treated liquid exits through the opposite side in the deepest part.

The water level in the system is controlled by a set of pipes, in the form of a pipe, known as a “monk.” To prevent coarse materials and grease from entering the Filter Garden filter media, a solids retention box and a grease trap are previously added to the treatment system.

 

 

Cost and resources

      • Approximately USD 1,000

 

Advantages

      • It is a nature-based technology that follows the principles of “constructed wetlands” or “root zone treatment” systems, increasing the sustainability of food production.
      • Technology can be used to expand access to basic sanitation and use of sustainable practices in rural communities.
      • The biofilter guarantees the safe reuse of treated effluents, with significant value in areas with limited access to agricultural water and nutrients, improving productivity and food security.

 

Complexity

Biofilter technology designed for small agricultural applications tends to be relatively simple, affordable, and easy to build and maintain. It involves the use of local materials and simple technology to reduce costs and complexity, so that farmers themselves can manage them without requiring specialized technical training.

 

 

 

Sources:

  • CARLOS LAÉCIO EVANGELISTA FRANCA; MIRIAM CLEIDE CAVALCANTE DE AMORIM; NELCI OLSZEVSKI; CLÉRISON DOS SANTOS BELÉM. Use of treated gray water in fruit irrigation in the semi-arid region: Legal aspects and soil quality. Revista Verde 17:3 (2022) 167-177.
  • WILSON TADEU LOPES DA SILVA, CARLOS RENATO MARMO, JOANA CASTURINA DA SILVA, EDILSON PEPINO FRAGALLE. 20 years of Rural Sanitation at Embrapa Instrumentation: from Basic to Environmental. DOCUMENTS 72. EMBRAPA. 2021